See if it's part of your wallet: click Help > Debug window > Console > enter listaddressgroupings.
See if it's in that list.
Or just dumpprivkey directly, import into Electrum, and be done with (if the address is yours).
It was the Bitcointalk forum that inspired us to create Bitcointalksearch.org - Bitcointalk is an excellent site that should be the default page for anybody dealing in cryptocurrency, since it is a virtual gold-mine of data. However, our experience and user feedback led us create our site; Bitcointalk's search is slow, and difficult to get the results you need, because you need to log in first to find anything useful - furthermore, there are rate limiters for their search functionality.
The aim of our project is to create a faster website that yields more results and faster without having to create an account and eliminate the need to log in - your personal data, therefore, will never be in jeopardy since we are not asking for any of your data and you don't need to provide them to use our site with all of its capabilities.
We created this website with the sole purpose of users being able to search quickly and efficiently in the field of cryptocurrency so they will have access to the latest and most accurate information and thereby assisting the crypto-community at large.
1Jxw2KfwDaVWgBZVsvdYLpT1Npyzf7cGTa 0.00100000 BTC Unspent
1Cb5Hk4FyY7wvTNkfZJCgdnCaj6tmgYh61 0.04517068 BTC Unspent
python pywallet.py --dumpwallet --wallet=wallet.dat
python pywallet.py --dumpwallet --passphrase=yourpassword123 --wallet=wallet.dat
1Jxw2KfwDaVWgBZVsvdYLpT1Npyzf7cGTa 0.00100000 BTC Unspent
1Cb5Hk4FyY7wvTNkfZJCgdnCaj6tmgYh61 0.04517068 BTC Unspent
open Bitcoin-Qt.app --args
open Bitcoin-Qt.app --args
getrawtransaction PASTE_THE_TRANSACTION_ID_HERE
getrawtransaction PASTE_THE_TRANSACTION_ID_HERE
sendrawtransaction COPY_PASTE_THE_HEX_FROM_ABOVE_HERE